Coordinate Regulation of Electrical Transport and Thermal Stability of BaSm2Ti4O12-δ Ceramics by (Tb, Zr) Codoping for High-Temperature Applications

Abstract

Coordinated regulation of electrical transport and high-temperature stability of BaSm₂Ti₄O_12-δ is essential for achieving precise temperature measurements in high-temperature thermistors. However, at higher temperatures, the increasing oxygen vacancies in BaSm₂Ti₄O_12-δ trigger a self-compensation effect that drives the delocalization of localized electronic states. This mechanism consequently induces deviation from the Arrhenius equation in the resistivity-temperature relationship. Herein, we propose a codoping strategy to suppress the high-temperature self-compensating effect of BaSm₂Ti₄O_12-δ. The codoping strategy comprises (i) substitutional incorporation of Tb^3.5+ (average valence) at Sm³⁺ sites to modulate oxygen vacancy concentration through charge compensation mechanisms and (ii) isovalent Zr⁴⁺ doping into Ti⁴⁺ sites to suppress Ti³⁺ formation via stabilization of the Ti-site oxidation state. The results indicate that introducing Zr, in conjunction with a Tb doping amount of 0.2 (BaTb_0.2Sm_1.8Zr_xTi_4–xO_12-δ), enhances the linear fitting coefficient of the resistance–temperature curve from 99.867% to 99.994% and reduces the aging drift rate from 86.45% to 3.1%. Additionally, the temperature coefficient of resistance (α_1000 °C) ranges from −0.89 to −1.18%/°C. (Tb, Zr) codoping improves the linearity of the resistance–temperature curve and the high-temperature stability of BaTb_0.2Sm_1.8Zr_xTi_4–xO_12-δ ceramics. This synergistic optimization offers insights for designing effective dopants in high-temperature thermosensitive materials.